Historically, acute myocardial infarction (AMI) has been diagnosed in a patient when at least two of the following three criteria are satisfied: (1) ischemic chest pain typically associated with AMI, (2) electrocardiogram (ECG) findings typically associated with AMI (e.g., ST segment elevation and pathological Q-waves), and (3) raised concentrations of the enzyme creatine kinase (CK) in serum. It has been difficult for prior medical devices, either implantable or external, to detect AMI with satisfactory levels of sensitivity and specificity using the above three criteria. This difficulty in detection has led to the late recognition of AMI and action by the patient in seeking assistance, thereby leading to long delays until therapies are delivered to the patient, such as fibrinolysis or percutaneous coronary intervention (PCI).